Mortising attachment for portable drill



Jan; 12, 1960 J. CZERNIEWICZ 2,920,662

' MORTIS ING ATTACHMENT FOR PORTABLE DRILL Filed Oct. 31. 1957 'vvvuvvuvuu vrvwvvv'v Jl 1 w T.

FLGI'A FlGl S Pa n Q p I J; 2,920,662 .MORTISING ATTACHMENT-FOR p PORTABLE DRILL" John Czerniewicm Mineola, N. Application October 31, 1957,Serial No. 693,656 4W.(r.144 m average amateur or home workman, .The only alternahe is'to do the job witha hand chisel-which is a tedious and inaccurate procedure and results in loose joints. However, most amateur workworkers have a portable electric drill, and the present invention provides an attachment for this basic tool which permits the conventional portable electric drill to be used for cutting neat, accurate and workmanlike slots and mortise joints.

The present invention generally comprises a guide or rack having a center slot and having a plurality of guide teeth along the sides of the slot. A cutting tool holder is adapted to be rotatably mounted between the teeth so as to drill a plurality of holes. The tool holder may also be rotated to cut away the scalloped edges between the irlrdividual holes left by the drill and to provide a smooth s ot.

Accordingly, a principal object of the invention is to provide new and improved woodworking means.

Another object of the invention is to provide new and improved means to adapt an electrical drill for cutting a slot or mortise joint.

Another object of the invention is to provide new and implroved means for cutting a slot with a rotating cutting 100 Another object of the invention is to provide new and improved means for cutting slots with a portable drill comprising a rack having a large slot and a plurality of guide teeth along the sides of said slot and cutting too-l holder adapted to be rotatably mounted between said guide teeth.

Another object of the invention is to provide new and improved means for accurately positioning and firmly securing a device for cutting a slot with a rotating and scillating cutting tool.

These and other objects of the invention will become apparent from the following specification and drawings, of which:

Figure 1 is a plan view of an embodiment of the invention.

Figure 1A is a detail view.-

Figure 2 is a side view of the embodiment of Figure 1.

Figure 3 is an enlarged sectional view of the cutting tool holder, and

Figure 4 is a diagram illustrating the use of the invention.

Referring to the drawings, the invention generally comprises a guide or rack having two identical side pieces 2 2,920,662 Patented Jan. 12,1960

. and 2'. which are adapted to be clamped together by the threaded'hooks 3 and "3 which fit between the teeth of side pieces, as shown in Figure 1A.

' that it will not rotate within the guide.

The guide is adapted to be fastened to the work piece by means of the thumb screws 5 and 5. These screws are so located that they serve to position and center the device, by being made to pierce a center line 24 or 24' which passes through the middle of the desired slot or mortise. The holes 21, 21' made by the thumb screws are generally covered by the shoulders of the tenon or mating piece or lock plate or may be filled. However, if it'is'desired to avoid any holes, the guide may be clamped into place or otherwise connected. However, these thumb screws have the advantage that they may be used at any point-on a large piece of wood whereas clamps can only be used near the edges.

Each side piece has a plurality of teeth a, b,- c, and so forth. The cutting tool holder 1 is generally square so Referring to Fig; ure 3 the cutting tool holder comprises a body member 12. havingtwo sets of bearings 10 and 11 which rotatably support journals 8 and 9 holding the shaft of the cutting tool '6 which may beheld in place by means of theset screw 17. A" springloaded guard 15 is slidably mounted on the body member 12 and' is spring loaded by the spring 16 which bears against the pin 13 which is fixed to the guard 15. The pin 13 rides in a slot 13 in the body member 12. The mounting pins 7 and 7 are mounted on the guard 15'and are not shown in Figure 3. When the cutting tool holder is mounted in the rack 2, 2 and pushed down, the cutting edges 6' of the cutting tool will be exposed since the guard 15 will ride up along the body member 12 until the top of the guard 15 rests against the adjustable stop nut 14, which is mounted on a threaded portion of the body member 12. Therefore, by adjusting the stopnut :14, the depth of the cut may be accurately controlled.

In operation, first the rack or guide is fastened to the work piece so that line 24, marking the middle of the proposed groove or mortise, is exactly in the middle of the working slot of the guide, and thumb screws 5 and 5' pierce line 24. The cutting tool holder 1 is then mounted in the rack with the portable electric drill, not shown, already connected to the shaft of the cutting tool 6. A series of holes 23 are then drilled generally outlining the desired slot by placing the tool holder 1 between different teeth of the rack. The depth may be accurately controlled by means of the depth adjustment 14. As the series of overlapping holes 23 are cut, there will be a scalloped edging left in the slot from the individual holes. This edging may be removed and the sides smoothed off as at 19 by rotating the tool holder about the axis of the pins 7 and 7', through a short are immediately after each succeeding hole is bored. A finished slot is shown at 20 ready to receive the mating piece 22 which may be easily notched with a hand saw.

Cutting tools of various width and size may be used and will be held by the journal members 8 and 9. The journal member 9 has an internal shape to conform to the outline of the cutting tools and, therefore, causes a cutting tool of any width to center itself. The journal members 8 and 9 are held together by the retaining tube 18 which holds the assembly together when the cutting tool is removed.

The cutting tool is preferably of the type shown in Figure 3 which is a flat plate drill having two cutting edges 6' which taper in towards the center. If this type of tool is not readily available, it may be easily ground down from a conventional flat drill of the type having a center point. This type cuttingtool is suitable for use i simple, quick and positive; 'ljhewidth is I the size of the cutting tool, the length by "th ting of the size of the rack, and

mi e? y nut '14. p

I Therefore, the present invention provides a simple and inexpensive attachment for portable, elect drills forg m slots and mortise i nts n, a: neat and. assume manner. Various. modifications may; be, made withoutdeparting from the scope of the invention which is :defined by the following claims.

' I claim:

1; Means for cutting a slot in wood-with a portable drill comprising a frame having a largefslot along its length and a plurality of largeuniformlyspaced guide teeth along both sides of said slot on one surface of sai d- Adjustments for width, length and. depth 'of; out are frame, a cutting tool holder for said d rillfh avirig of coaxial pins one on each side thereof; said lder being adapted to fit in said slot, said pins. adapted to between said teeth to mount said tool holder for rotation in the plane of the axis of said slot:

2. Means for cutting a slot in wood with a portable drill comprising a flat normally horizontal narrow frame having a lengthwise slot extending vertically through said frame and a plurality of guide teeth uniformly spaced along both sides of said slot onthe upper surface of said frame, and a cutting toolholder adapted to be mounted between said teeth. at different p intspalvongpslaid fr said tool holder having: a sliding'jguard to shield a cutting tool in said. holder;whe n v saidholder is withdrawn from saidrack. I

3. Apparatusasiu: claiml wh rein; saidrmemhers have adjustable connecting means to adjust, the length of said Slot. 4 a a 4. Apparatus as in claim 2 wherein said cutting tool holder has depth adjustment means.

References, Giteddn the 'file of. this patent 1 ut-Easiest ta EaE S;

34 3 h s n v .r 4 1111,1 13; 1,88 1362x0 1; i r 1,921 69 0 g l 2 91 1,718,324 n 1929; 1,752,457 4 1 5 EOREIGNLPATENTS' a Y .026 Ge any Bela. ,892, 475 964 1929; 

